With the first degree murder charge it sounds like we are missing some details. Just speculating but, perhaps some threats beforehand in person or in the form of phone, maybe face book, where the shooter had the chance to have a premeditated response to something. A threat of “I’m going to blow up your car and burn down your house while you are asleep” could predispose someone to shoot first and ask questions later. The shooter might just be a notecase. There are people that will try to kill you for walking on their lawn